package com.silencedut.baselib.commonhelper.log;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.io.ObjectInputStream;
import java.text.DateFormat;
import java.text.DateFormatSymbols;
import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * <p>
 * FastDateFormat is a fast and thread-safe version of
 * {@link java.text.SimpleDateFormat}.
 * </p>
 * 
 * <p>
 * This class can be used as a direct replacement to {@code SimpleDateFormat} in
 * most formatting situations. This class is especially useful in multi-threaded
 * server environments. {@code SimpleDateFormat} is not thread-safe in any JDK
 * version, nor will it be as Sun have closed the bug/RFE.
 * </p>
 * 
 * <p>
 * Only formatting is supported, but all patterns are compatible with
 * SimpleDateFormat (except time zones and some year patterns - see below).
 * </p>
 * 
 * <p>
 * Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent time
 * zones in RFC822 format (eg. {@code +0800} or {@code -1100}). This pattern
 * letter can be used here (on all JDK versions).
 * </p>
 * 
 * <p>
 * In addition, the pattern {@code 'ZZ'} has been made to represent ISO8601 full
 * format time zones (eg. {@code +08:00} or {@code -11:00}). This introduces a
 * minor incompatibility with Java 1.4, but at a gain of useful functionality.
 * </p>
 * 
 * <p>
 * Javadoc cites for the year pattern: <info>For formatting, if the number of
 * pattern letters is 2, the year is truncated to 2 digits; otherwise it is
 * interpreted as a number.</info> Starting with Java 1.7 a pattern of 'Y' or 'YYY'
 * will be formatted as '2003', while it was '03' in former Java versions.
 * FastDateFormat implements the behavior of Java 7.
 * </p>
 * 
 * @since 2.0
 * @version $Id: FastDateFormat.java 1146138 2011-07-13 17:01:37Z joehni $
 */
class FastDateFormat extends Format {
	// A lot of the speed in this class comes from caching, but some comes
	// from the special int to StringBuffer conversion.
	//
	// The following produces a padded 2 digit number:
	// buffer.append((char)(value / 10 + '0'));
	// buffer.append((char)(value % 10 + '0'));
	//
	// Note that the fastest append to StringBuffer is a single char (used
	// here).
	// Note that Integer.toString() is not called, the conversion is simply
	// taking the value and adding (mathematically) the ASCII value for '0'.
	// So, don't change this code! It works and is very fast.

	/**
	 * Required for serialization support.
	 * 
	 * @see java.io.Serializable
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * FULL locale dependent date or time style.
	 */
	public static final int FULL = DateFormat.FULL;
	/**
	 * LONG locale dependent date or time style.
	 */
	public static final int LONG = DateFormat.LONG;
	/**
	 * MEDIUM locale dependent date or time style.
	 */
	public static final int MEDIUM = DateFormat.MEDIUM;
	/**
	 * SHORT locale dependent date or time style.
	 */
	public static final int SHORT = DateFormat.SHORT;

	private static final FormatCache<FastDateFormat> cache = new FormatCache<FastDateFormat>() {
		@Override
		protected FastDateFormat createInstance(String pattern,
                                                TimeZone timeZone, Locale locale) {
			return new FastDateFormat(pattern, timeZone, locale);
		}
	};

	private static ConcurrentMap<TimeZoneDisplayKey, String> cTimeZoneDisplayCache = new ConcurrentHashMap<TimeZoneDisplayKey, String>(
			7);

	/**
	 * The pattern.
	 */
	private final String mPattern;
	/**
	 * The time zone.
	 */
	private final TimeZone mTimeZone;
	/**
	 * The locale.
	 */
	private final Locale mLocale;
	/**
	 * The parsed rules.
	 */
	private transient Rule[] mRules;
	/**
	 * The estimated maximum length.
	 */
	private transient int mMaxLengthEstimate;

	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets a formatter instance using the default pattern in the default
	 * locale.
	 * </p>
	 * 
	 * @return a date/time formatter
	 */
	public static FastDateFormat getInstance() {
		return cache.getDateTimeInstance(SHORT, SHORT, null, null);
	}

	/**
	 * <p>
	 * Gets a formatter instance using the specified pattern in the default
	 * locale.
	 * </p>
	 * 
	 * @param pattern
	 *            {@link java.text.SimpleDateFormat} compatible pattern
	 * @return a pattern based date/time formatter
	 * @throws IllegalArgumentException
	 *             if pattern is invalid
	 */
	public static FastDateFormat getInstance(String pattern) {
		return cache.getInstance(pattern, null, null);
	}

	/**
	 * <p>
	 * Gets a formatter instance using the specified pattern and time zone.
	 * </p>
	 * 
	 * @param pattern
	 *            {@link java.text.SimpleDateFormat} compatible pattern
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @return a pattern based date/time formatter
	 * @throws IllegalArgumentException
	 *             if pattern is invalid
	 */
	public static FastDateFormat getInstance(String pattern, TimeZone timeZone) {
		return cache.getInstance(pattern, timeZone, null);
	}

	/**
	 * <p>
	 * Gets a formatter instance using the specified pattern and locale.
	 * </p>
	 * 
	 * @param pattern
	 *            {@link java.text.SimpleDateFormat} compatible pattern
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a pattern based date/time formatter
	 * @throws IllegalArgumentException
	 *             if pattern is invalid
	 */
	public static FastDateFormat getInstance(String pattern, Locale locale) {
		return cache.getInstance(pattern, null, locale);
	}

	/**
	 * <p>
	 * Gets a formatter instance using the specified pattern, time zone and
	 * locale.
	 * </p>
	 * 
	 * @param pattern
	 *            {@link java.text.SimpleDateFormat} compatible pattern
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a pattern based date/time formatter
	 * @throws IllegalArgumentException
	 *             if pattern is invalid or {@code null}
	 */
	public static FastDateFormat getInstance(String pattern, TimeZone timeZone,
                                             Locale locale) {
		return cache.getInstance(pattern, timeZone, locale);
	}

	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets a date formatter instance using the specified style in the default
	 * time zone and locale.
	 * </p>
	 * 
	 * @param style
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @return a localized standard date formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateInstance(int style) {
		return cache.getDateTimeInstance(style, null, null, null);
	}

	/**
	 * <p>
	 * Gets a date formatter instance using the specified style and locale in
	 * the default time zone.
	 * </p>
	 * 
	 * @param style
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard date formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateInstance(int style, Locale locale) {
		return cache.getDateTimeInstance(style, null, null, locale);
	}

	/**
	 * <p>
	 * Gets a date formatter instance using the specified style and time zone in
	 * the default locale.
	 * </p>
	 * 
	 * @param style
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @return a localized standard date formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateInstance(int style, TimeZone timeZone) {
		return cache.getDateTimeInstance(style, null, timeZone, null);
	}

	/**
	 * <p>
	 * Gets a date formatter instance using the specified style, time zone and
	 * locale.
	 * </p>
	 * 
	 * @param style
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard date formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date pattern defined
	 */
	public static FastDateFormat getDateInstance(int style, TimeZone timeZone,
												 Locale locale) {
		return cache.getDateTimeInstance(style, null, timeZone, locale);
	}

	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets a time formatter instance using the specified style in the default
	 * time zone and locale.
	 * </p>
	 * 
	 * @param style
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @return a localized standard time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getTimeInstance(int style) {
		return cache.getDateTimeInstance(null, style, null, null);
	}

	/**
	 * <p>
	 * Gets a time formatter instance using the specified style and locale in
	 * the default time zone.
	 * </p>
	 * 
	 * @param style
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getTimeInstance(int style, Locale locale) {
		return cache.getDateTimeInstance(null, style, null, locale);
	}

	/**
	 * <p>
	 * Gets a time formatter instance using the specified style and time zone in
	 * the default locale.
	 * </p>
	 * 
	 * @param style
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted time
	 * @return a localized standard time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getTimeInstance(int style, TimeZone timeZone) {
		return cache.getDateTimeInstance(null, style, timeZone, null);
	}

	/**
	 * <p>
	 * Gets a time formatter instance using the specified style, time zone and
	 * locale.
	 * </p>
	 * 
	 * @param style
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted time
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no time pattern defined
	 */
	public static FastDateFormat getTimeInstance(int style, TimeZone timeZone,
												 Locale locale) {
		return cache.getDateTimeInstance(null, style, timeZone, locale);
	}

	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets a date/time formatter instance using the specified style in the
	 * default time zone and locale.
	 * </p>
	 * 
	 * @param dateStyle
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeStyle
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @return a localized standard date/time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date/time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateTimeInstance(int dateStyle,
													 int timeStyle) {
		return cache.getDateTimeInstance(dateStyle, timeStyle, null, null);
	}

	/**
	 * <p>
	 * Gets a date/time formatter instance using the specified style and locale
	 * in the default time zone.
	 * </p>
	 * 
	 * @param dateStyle
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeStyle
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard date/time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date/time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateTimeInstance(int dateStyle,
													 int timeStyle, Locale locale) {
		return cache.getDateTimeInstance(dateStyle, timeStyle, null, locale);
	}

	/**
	 * <p>
	 * Gets a date/time formatter instance using the specified style and time
	 * zone in the default locale.
	 * </p>
	 * 
	 * @param dateStyle
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeStyle
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @return a localized standard date/time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date/time pattern defined
	 * @since 2.1
	 */
	public static FastDateFormat getDateTimeInstance(int dateStyle,
													 int timeStyle, TimeZone timeZone) {
		return getDateTimeInstance(dateStyle, timeStyle, timeZone, null);
	}

	/**
	 * <p>
	 * Gets a date/time formatter instance using the specified style, time zone
	 * and locale.
	 * </p>
	 * 
	 * @param dateStyle
	 *            date style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeStyle
	 *            time style: FULL, LONG, MEDIUM, or SHORT
	 * @param timeZone
	 *            optional time zone, overrides time zone of formatted date
	 * @param locale
	 *            optional locale, overrides system locale
	 * @return a localized standard date/time formatter
	 * @throws IllegalArgumentException
	 *             if the Locale has no date/time pattern defined
	 */
	public static FastDateFormat getDateTimeInstance(int dateStyle,
                                                     int timeStyle, TimeZone timeZone, Locale locale) {
		return cache
				.getDateTimeInstance(dateStyle, timeStyle, timeZone, locale);
	}

	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets the time zone display name, using a cache for performance.
	 * </p>
	 * 
	 * @param tz
	 *            the zone to query
	 * @param daylight
	 *            true if daylight savings
	 * @param style
	 *            the style to use {@code TimeZone.LONG} or
	 *            {@code TimeZone.SHORT}
	 * @param locale
	 *            the locale to use
	 * @return the textual name of the time zone
	 */
	static String getTimeZoneDisplay(TimeZone tz, boolean daylight, int style,
                                     Locale locale) {
		TimeZoneDisplayKey key = new TimeZoneDisplayKey(tz, daylight, style,
				locale);
		String value = cTimeZoneDisplayCache.get(key);
		if (value == null) {
			// This is a very slow call, so cache the results.
			value = tz.getDisplayName(daylight, style, locale);
			String prior = cTimeZoneDisplayCache.putIfAbsent(key, value);
			if (prior != null) {
				value = prior;
			}
		}
		return value;
	}

	// Constructor
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Constructs a new FastDateFormat.
	 * </p>
	 * 
	 * @param pattern
	 *            {@link java.text.SimpleDateFormat} compatible pattern
	 * @param timeZone
	 *            non-null time zone to use
	 * @param locale
	 *            non-null locale to use
	 * @throws NullPointerException
	 *             if pattern, timeZone, or locale is null.
	 */
	protected FastDateFormat(String pattern, TimeZone timeZone, Locale locale) {
		mPattern = pattern;
		mTimeZone = timeZone;
		mLocale = locale;

		init();
	}

	/**
	 * <p>
	 * Initializes the instance for first use.
	 * </p>
	 */
	private void init() {
		List<Rule> rulesList = parsePattern();
		mRules = rulesList.toArray(new Rule[rulesList.size()]);

		int len = 0;
		for (int i = mRules.length; --i >= 0;) {
			len += mRules[i].estimateLength();
		}

		mMaxLengthEstimate = len;
	}

	// Parse the pattern
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Returns a list of Rules given a pattern.
	 * </p>
	 * 
	 * @return a {@code List} of Rule objects
	 * @throws IllegalArgumentException
	 *             if pattern is invalid
	 */
	protected List<Rule> parsePattern() {
		DateFormatSymbols symbols = new DateFormatSymbols(mLocale);
		List<Rule> rules = new ArrayList<Rule>();

		String[] ERAs = symbols.getEras();
		String[] months = symbols.getMonths();
		String[] shortMonths = symbols.getShortMonths();
		String[] weekdays = symbols.getWeekdays();
		String[] shortWeekdays = symbols.getShortWeekdays();
		String[] AmPmStrings = symbols.getAmPmStrings();

		int length = mPattern.length();
		int[] indexRef = new int[1];

		for (int i = 0; i < length; i++) {
			indexRef[0] = i;
			String token = parseToken(mPattern, indexRef);
			i = indexRef[0];

			int tokenLen = token.length();
			if (tokenLen == 0) {
				break;
			}

			Rule rule;
			char c = token.charAt(0);

			switch (c) {
			case 'G': // era designator (text)
				rule = new TextField(Calendar.ERA, ERAs);
				break;
			case 'y': // year (number)
				if (tokenLen == 2) {
					rule = TwoDigitYearField.INSTANCE;
				} else {
					rule = selectNumberRule(Calendar.YEAR, tokenLen < 4 ? 4
							: tokenLen);
				}
				break;
			case 'M': // month in year (text and number)
				if (tokenLen >= 4) {
					rule = new TextField(Calendar.MONTH, months);
				} else if (tokenLen == 3) {
					rule = new TextField(Calendar.MONTH, shortMonths);
				} else if (tokenLen == 2) {
					rule = TwoDigitMonthField.INSTANCE;
				} else {
					rule = UnpaddedMonthField.INSTANCE;
				}
				break;
			case 'd': // day in month (number)
				rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
				break;
			case 'h': // hour in am/pm (number, 1..12)
				rule = new TwelveHourField(selectNumberRule(Calendar.HOUR,
						tokenLen));
				break;
			case 'H': // hour in day (number, 0..23)
				rule = selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen);
				break;
			case 'm': // minute in hour (number)
				rule = selectNumberRule(Calendar.MINUTE, tokenLen);
				break;
			case 's': // second in minute (number)
				rule = selectNumberRule(Calendar.SECOND, tokenLen);
				break;
			case 'S': // millisecond (number)
				rule = selectNumberRule(Calendar.MILLISECOND, tokenLen);
				break;
			case 'E': // day in week (text)
				rule = new TextField(Calendar.DAY_OF_WEEK,
						tokenLen < 4 ? shortWeekdays : weekdays);
				break;
			case 'D': // day in year (number)
				rule = selectNumberRule(Calendar.DAY_OF_YEAR, tokenLen);
				break;
			case 'F': // day of week in month (number)
				rule = selectNumberRule(Calendar.DAY_OF_WEEK_IN_MONTH, tokenLen);
				break;
			case 'w': // week in year (number)
				rule = selectNumberRule(Calendar.WEEK_OF_YEAR, tokenLen);
				break;
			case 'W': // week in month (number)
				rule = selectNumberRule(Calendar.WEEK_OF_MONTH, tokenLen);
				break;
			case 'a': // am/pm marker (text)
				rule = new TextField(Calendar.AM_PM, AmPmStrings);
				break;
			case 'k': // hour in day (1..24)
				rule = new TwentyFourHourField(selectNumberRule(
						Calendar.HOUR_OF_DAY, tokenLen));
				break;
			case 'K': // hour in am/pm (0..11)
				rule = selectNumberRule(Calendar.HOUR, tokenLen);
				break;
			case 'z': // time zone (text)
				if (tokenLen >= 4) {
					rule = new TimeZoneNameRule(mTimeZone, mLocale,
							TimeZone.LONG);
				} else {
					rule = new TimeZoneNameRule(mTimeZone, mLocale,
							TimeZone.SHORT);
				}
				break;
			case 'Z': // time zone (value)
				if (tokenLen == 1) {
					rule = TimeZoneNumberRule.INSTANCE_NO_COLON;
				} else {
					rule = TimeZoneNumberRule.INSTANCE_COLON;
				}
				break;
			case '\'': // literal text
				String sub = token.substring(1);
				if (sub.length() == 1) {
					rule = new CharacterLiteral(sub.charAt(0));
				} else {
					rule = new StringLiteral(sub);
				}
				break;
			default:
				throw new IllegalArgumentException(
						"Illegal pattern component: " + token);
			}

			rules.add(rule);
		}

		return rules;
	}

	/**
	 * <p>
	 * Performs the parsing of tokens.
	 * </p>
	 * 
	 * @param pattern
	 *            the pattern
	 * @param indexRef
	 *            index references
	 * @return parsed token
	 */
	protected String parseToken(String pattern, int[] indexRef) {
		StringBuilder buf = new StringBuilder();

		int i = indexRef[0];
		int length = pattern.length();

		char c = pattern.charAt(i);
		if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {
			// Scan a run of the same character, which indicates a time
			// pattern.
			buf.append(c);

			while (i + 1 < length) {
				char peek = pattern.charAt(i + 1);
				if (peek == c) {
					buf.append(c);
					i++;
				} else {
					break;
				}
			}
		} else {
			// This will identify token as text.
			buf.append('\'');

			boolean inLiteral = false;

			for (; i < length; i++) {
				c = pattern.charAt(i);

				if (c == '\'') {
					if (i + 1 < length && pattern.charAt(i + 1) == '\'') {
						// '' is treated as escaped '
						i++;
						buf.append(c);
					} else {
						inLiteral = !inLiteral;
					}
				} else if (!inLiteral
						&& (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z')) {
					i--;
					break;
				} else {
					buf.append(c);
				}
			}
		}

		indexRef[0] = i;
		return buf.toString();
	}

	/**
	 * <p>
	 * Gets an appropriate rule for the padding required.
	 * </p>
	 * 
	 * @param field
	 *            the field to get a rule for
	 * @param padding
	 *            the padding required
	 * @return a new rule with the correct padding
	 */
	protected NumberRule selectNumberRule(int field, int padding) {
		switch (padding) {
		case 1:
			return new UnpaddedNumberField(field);
		case 2:
			return new TwoDigitNumberField(field);
		default:
			return new PaddedNumberField(field, padding);
		}
	}

	// Format methods
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Formats a {@code Date}, {@code Calendar} or {@code Long} (milliseconds)
	 * object.
	 * </p>
	 * 
	 * @param obj
	 *            the object to format
	 * @param toAppendTo
	 *            the buffer to append to
	 * @param pos
	 *            the position - ignored
	 * @return the buffer passed in
	 */
	@Override
	public StringBuffer format(Object obj, StringBuffer toAppendTo,
                               FieldPosition pos) {
		if (obj instanceof Date) {
			return format((Date) obj, toAppendTo);
		} else if (obj instanceof Calendar) {
			return format((Calendar) obj, toAppendTo);
		} else if (obj instanceof Long) {
			return format(((Long) obj).longValue(), toAppendTo);
		} else {
			throw new IllegalArgumentException("Unknown class: "
					+ (obj == null ? "<null>" : obj.getClass().getName()));
		}
	}

	/**
	 * <p>
	 * Formats a millisecond {@code long} value.
	 * </p>
	 * 
	 * @param millis
	 *            the millisecond value to format
	 * @return the formatted string
	 * @since 2.1
	 */
	public String format(long millis) {
		return format(new Date(millis));
	}

	/**
	 * <p>
	 * Formats a {@code Date} object using a {@code GregorianCalendar}.
	 * </p>
	 * 
	 * @param date
	 *            the date to format
	 * @return the formatted string
	 */
	public String format(Date date) {
		Calendar c = new GregorianCalendar(mTimeZone, mLocale); // hard code
																// GregorianCalendar
		c.setTime(date);
		return applyRules(c, new StringBuffer(mMaxLengthEstimate)).toString();
	}

	/**
	 * <p>
	 * Formats a {@code Calendar} object.
	 * </p>
	 * 
	 * @param calendar
	 *            the calendar to format
	 * @return the formatted string
	 */
	public String format(Calendar calendar) {
		return format(calendar, new StringBuffer(mMaxLengthEstimate))
				.toString();
	}

	/**
	 * <p>
	 * Formats a milliseond {@code long} value into the supplied
	 * {@code StringBuffer}.
	 * </p>
	 * 
	 * @param millis
	 *            the millisecond value to format
	 * @param buf
	 *            the buffer to format into
	 * @return the specified string buffer
	 * @since 2.1
	 */
	public StringBuffer format(long millis, StringBuffer buf) {
		return format(new Date(millis), buf);
	}

	/**
	 * <p>
	 * Formats a {@code Date} object into the supplied {@code StringBuffer}
	 * using a {@code GregorianCalendar}.
	 * </p>
	 * 
	 * @param date
	 *            the date to format
	 * @param buf
	 *            the buffer to format into
	 * @return the specified string buffer
	 */
	public StringBuffer format(Date date, StringBuffer buf) {
		Calendar c = new GregorianCalendar(mTimeZone, mLocale); // hard code
																// GregorianCalendar
		c.setTime(date);
		return applyRules(c, buf);
	}

	/**
	 * <p>
	 * Formats a {@code Calendar} object into the supplied {@code StringBuffer}.
	 * </p>
	 * 
	 * @param calendar
	 *            the calendar to format
	 * @param buf
	 *            the buffer to format into
	 * @return the specified string buffer
	 */
	public StringBuffer format(Calendar calendar, StringBuffer buf) {
		return applyRules(calendar, buf);
	}

	/**
	 * <p>
	 * Performs the formatting by applying the rules to the specified calendar.
	 * </p>
	 * 
	 * @param calendar
	 *            the calendar to format
	 * @param buf
	 *            the buffer to format into
	 * @return the specified string buffer
	 */
	protected StringBuffer applyRules(Calendar calendar, StringBuffer buf) {
		for (Rule rule : mRules) {
			rule.appendTo(buf, calendar);
		}
		return buf;
	}

	// Parsing
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Parsing is not supported.
	 * </p>
	 * 
	 * @param source
	 *            the string to parse
	 * @param pos
	 *            the parsing position
	 * @return {@code null} as not supported
	 */
	@Override
	public Object parseObject(String source, ParsePosition pos) {
		pos.setIndex(0);
		pos.setErrorIndex(0);
		return null;
	}

	// Accessors
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets the pattern used by this formatter.
	 * </p>
	 * 
	 * @return the pattern, {@link java.text.SimpleDateFormat} compatible
	 */
	public String getPattern() {
		return mPattern;
	}

	/**
	 * <p>
	 * Gets the time zone used by this formatter.
	 * </p>
	 * 
	 * <p>
	 * This zone is always used for {@code Date} formatting.
	 * </p>
	 * 
	 * @return the time zone
	 */
	public TimeZone getTimeZone() {
		return mTimeZone;
	}

	/**
	 * <p>
	 * Gets the locale used by this formatter.
	 * </p>
	 * 
	 * @return the locale
	 */
	public Locale getLocale() {
		return mLocale;
	}

	/**
	 * <p>
	 * Gets an estimate for the maximum string length that the formatter will
	 * produce.
	 * </p>
	 * 
	 * <p>
	 * The actual formatted length will almost always be less than or equal to
	 * this amount.
	 * </p>
	 * 
	 * @return the maximum formatted length
	 */
	public int getMaxLengthEstimate() {
		return mMaxLengthEstimate;
	}

	// Basics
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Compares two objects for equality.
	 * </p>
	 * 
	 * @param obj
	 *            the object to compare to
	 * @return {@code true} if equal
	 */
	@Override
	public boolean equals(Object obj) {
		if (obj instanceof FastDateFormat == false) {
			return false;
		}
		FastDateFormat other = (FastDateFormat) obj;
		return mPattern.equals(other.mPattern)
				&& mTimeZone.equals(other.mTimeZone)
				&& mLocale.equals(other.mLocale);
	}

	/**
	 * <p>
	 * Returns a hashcode compatible with equals.
	 * </p>
	 * 
	 * @return a hashcode compatible with equals
	 */
	@Override
	public int hashCode() {
		return mPattern.hashCode() + 13
				* (mTimeZone.hashCode() + 13 * mLocale.hashCode());
	}

	/**
	 * <p>
	 * Gets a debugging string version of this formatter.
	 * </p>
	 * 
	 * @return a debugging string
	 */
	@Override
	public String toString() {
		return "FastDateFormat[" + mPattern + "]";
	}

	// Serializing
	// -----------------------------------------------------------------------
	/**
	 * Create the object after serialization. This implementation reinitializes
	 * the transient properties.
	 * 
	 * @param in
	 *            ObjectInputStream from which the object is being deserialized.
	 * @throws IOException
	 *             if there is an IO issue.
	 * @throws ClassNotFoundException
	 *             if a class cannot be found.
	 */
	private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
		in.defaultReadObject();
		init();
	}

	// Rules
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Inner class defining a rule.
	 * </p>
	 */
	private interface Rule {
		/**
		 * Returns the estimated lentgh of the result.
		 * 
		 * @return the estimated length
		 */
		int estimateLength();

		/**
		 * Appends the value of the specified calendar to the output buffer
		 * based on the rule implementation.
		 * 
		 * @param buffer
		 *            the output buffer
		 * @param calendar
		 *            calendar to be appended
		 */
		void appendTo(StringBuffer buffer, Calendar calendar);
	}

	/**
	 * <p>
	 * Inner class defining a numeric rule.
	 * </p>
	 */
	private interface NumberRule extends Rule {
		/**
		 * Appends the specified value to the output buffer based on the rule
		 * implementation.
		 * 
		 * @param buffer
		 *            the output buffer
		 * @param value
		 *            the value to be appended
		 */
		void appendTo(StringBuffer buffer, int value);
	}

	/**
	 * <p>
	 * Inner class to output a constant single character.
	 * </p>
	 */
	private static class CharacterLiteral implements Rule {
		private final char mValue;

		/**
		 * Constructs a new instance of {@code CharacterLiteral} to hold the
		 * specified value.
		 * 
		 * @param value
		 *            the character literal
		 */
		CharacterLiteral(char value) {
			mValue = value;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 1;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			buffer.append(mValue);
		}
	}

	/**
	 * <p>
	 * Inner class to output a constant string.
	 * </p>
	 */
	private static class StringLiteral implements Rule {
		private final String mValue;

		/**
		 * Constructs a new instance of {@code StringLiteral} to hold the
		 * specified value.
		 * 
		 * @param value
		 *            the string literal
		 */
		StringLiteral(String value) {
			mValue = value;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return mValue.length();
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			buffer.append(mValue);
		}
	}

	/**
	 * <p>
	 * Inner class to output one of a set of values.
	 * </p>
	 */
	private static class TextField implements Rule {
		private final int mField;
		private final String[] mValues;

		/**
		 * Constructs an instance of {@code TextField} with the specified field
		 * and values.
		 * 
		 * @param field
		 *            the field
		 * @param values
		 *            the field values
		 */
		TextField(int field, String[] values) {
			mField = field;
			mValues = values;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			int max = 0;
			for (int i = mValues.length; --i >= 0;) {
				int len = mValues[i].length();
				if (len > max) {
					max = len;
				}
			}
			return max;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			buffer.append(mValues[calendar.get(mField)]);
		}
	}

	/**
	 * <p>
	 * Inner class to output an unpadded number.
	 * </p>
	 */
	private static class UnpaddedNumberField implements NumberRule {
		private final int mField;

		/**
		 * Constructs an instance of {@code UnpadedNumberField} with the
		 * specified field.
		 * 
		 * @param field
		 *            the field
		 */
		UnpaddedNumberField(int field) {
			mField = field;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 4;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			if (value < 10) {
				buffer.append((char) (value + '0'));
			} else if (value < 100) {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>
	 * Inner class to output an unpadded month.
	 * </p>
	 */
	private static class UnpaddedMonthField implements NumberRule {
		static final UnpaddedMonthField INSTANCE = new UnpaddedMonthField();

		/**
		 * Constructs an instance of {@code UnpaddedMonthField}.
		 * 
		 */
		UnpaddedMonthField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			if (value < 10) {
				buffer.append((char) (value + '0'));
			} else {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			}
		}
	}

	/**
	 * <p>
	 * Inner class to output a padded number.
	 * </p>
	 */
	private static class PaddedNumberField implements NumberRule {
		private final int mField;
		private final int mSize;

		/**
		 * Constructs an instance of {@code PaddedNumberField}.
		 * 
		 * @param field
		 *            the field
		 * @param size
		 *            size of the output field
		 */
		PaddedNumberField(int field, int size) {
			if (size < 3) {
				// Should use UnpaddedNumberField or TwoDigitNumberField.
				throw new IllegalArgumentException();
			}
			mField = field;
			mSize = size;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 4;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			if (value < 100) {
				for (int i = mSize; --i >= 2;) {
					buffer.append('0');
				}
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				int digits;
				if (value < 1000) {
					digits = 3;
				} else {
					digits = Integer.toString(value).length();
				}
				for (int i = mSize; --i >= digits;) {
					buffer.append('0');
				}
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>
	 * Inner class to output a two digit number.
	 * </p>
	 */
	private static class TwoDigitNumberField implements NumberRule {
		private final int mField;

		/**
		 * Constructs an instance of {@code TwoDigitNumberField} with the
		 * specified field.
		 * 
		 * @param field
		 *            the field
		 */
		TwoDigitNumberField(int field) {
			mField = field;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			if (value < 100) {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>
	 * Inner class to output a two digit year.
	 * </p>
	 */
	private static class TwoDigitYearField implements NumberRule {
		static final TwoDigitYearField INSTANCE = new TwoDigitYearField();

		/**
		 * Constructs an instance of {@code TwoDigitYearField}.
		 */
		TwoDigitYearField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.YEAR) % 100);
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			buffer.append((char) (value / 10 + '0'));
			buffer.append((char) (value % 10 + '0'));
		}
	}

	/**
	 * <p>
	 * Inner class to output a two digit month.
	 * </p>
	 */
	private static class TwoDigitMonthField implements NumberRule {
		static final TwoDigitMonthField INSTANCE = new TwoDigitMonthField();

		/**
		 * Constructs an instance of {@code TwoDigitMonthField}.
		 */
		TwoDigitMonthField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
		}

		/**
		 * {@inheritDoc}
		 */
		public final void appendTo(StringBuffer buffer, int value) {
			buffer.append((char) (value / 10 + '0'));
			buffer.append((char) (value % 10 + '0'));
		}
	}

	/**
	 * <p>
	 * Inner class to output the twelve hour field.
	 * </p>
	 */
	private static class TwelveHourField implements NumberRule {
		private final NumberRule mRule;

		/**
		 * Constructs an instance of {@code TwelveHourField} with the specified
		 * {@code NumberRule}.
		 * 
		 * @param rule
		 *            the rule
		 */
		TwelveHourField(NumberRule rule) {
			mRule = rule;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return mRule.estimateLength();
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			int value = calendar.get(Calendar.HOUR);
			if (value == 0) {
				value = calendar.getLeastMaximum(Calendar.HOUR) + 1;
			}
			mRule.appendTo(buffer, value);
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, int value) {
			mRule.appendTo(buffer, value);
		}
	}

	/**
	 * <p>
	 * Inner class to output the twenty four hour field.
	 * </p>
	 */
	private static class TwentyFourHourField implements NumberRule {
		private final NumberRule mRule;

		/**
		 * Constructs an instance of {@code TwentyFourHourField} with the
		 * specified {@code NumberRule}.
		 * 
		 * @param rule
		 *            the rule
		 */
		TwentyFourHourField(NumberRule rule) {
			mRule = rule;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return mRule.estimateLength();
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			int value = calendar.get(Calendar.HOUR_OF_DAY);
			if (value == 0) {
				value = calendar.getMaximum(Calendar.HOUR_OF_DAY) + 1;
			}
			mRule.appendTo(buffer, value);
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, int value) {
			mRule.appendTo(buffer, value);
		}
	}

	/**
	 * <p>
	 * Inner class to output a time zone name.
	 * </p>
	 */
	private static class TimeZoneNameRule implements Rule {
		private final TimeZone mTimeZone;
		private final String mStandard;
		private final String mDaylight;

		/**
		 * Constructs an instance of {@code TimeZoneNameRule} with the specified
		 * properties.
		 * 
		 * @param timeZone
		 *            the time zone
		 * @param locale
		 *            the locale
		 * @param style
		 *            the style
		 */
		TimeZoneNameRule(TimeZone timeZone, Locale locale, int style) {
			mTimeZone = timeZone;

			mStandard = getTimeZoneDisplay(timeZone, false, style, locale);
			mDaylight = getTimeZoneDisplay(timeZone, true, style, locale);
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return Math.max(mStandard.length(), mDaylight.length());
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			if (mTimeZone.useDaylightTime()
					&& calendar.get(Calendar.DST_OFFSET) != 0) {
				buffer.append(mDaylight);
			} else {
				buffer.append(mStandard);
			}
		}
	}

	/**
	 * <p>
	 * Inner class to output a time zone as a number {@code +/-HHMM} or
	 * {@code +/-HH:MM}.
	 * </p>
	 */
	private static class TimeZoneNumberRule implements Rule {
		static final TimeZoneNumberRule INSTANCE_COLON = new TimeZoneNumberRule(
				true);
		static final TimeZoneNumberRule INSTANCE_NO_COLON = new TimeZoneNumberRule(
				false);

		final boolean mColon;

		/**
		 * Constructs an instance of {@code TimeZoneNumberRule} with the
		 * specified properties.
		 * 
		 * @param colon
		 *            add colon between HH and MM in the output if {@code true}
		 */
		TimeZoneNumberRule(boolean colon) {
			mColon = colon;
		}

		/**
		 * {@inheritDoc}
		 */
		public int estimateLength() {
			return 5;
		}

		/**
		 * {@inheritDoc}
		 */
		public void appendTo(StringBuffer buffer, Calendar calendar) {
			int offset = calendar.get(Calendar.ZONE_OFFSET)
					+ calendar.get(Calendar.DST_OFFSET);

			if (offset < 0) {
				buffer.append('-');
				offset = -offset;
			} else {
				buffer.append('+');
			}

			int hours = offset / (60 * 60 * 1000);
			buffer.append((char) (hours / 10 + '0'));
			buffer.append((char) (hours % 10 + '0'));

			if (mColon) {
				buffer.append(':');
			}

			int minutes = offset / (60 * 1000) - 60 * hours;
			buffer.append((char) (minutes / 10 + '0'));
			buffer.append((char) (minutes % 10 + '0'));
		}
	}

	// ----------------------------------------------------------------------
	/**
	 * <p>
	 * Inner class that acts as a compound key for time zone names.
	 * </p>
	 */
	private static class TimeZoneDisplayKey {
		private final TimeZone mTimeZone;
		private final int mStyle;
		private final Locale mLocale;

		/**
		 * Constructs an instance of {@code TimeZoneDisplayKey} with the
		 * specified properties.
		 * 
		 * @param timeZone
		 *            the time zone
		 * @param daylight
		 *            adjust the style for daylight saving time if {@code true}
		 * @param style
		 *            the timezone style
		 * @param locale
		 *            the timezone locale
		 */
		TimeZoneDisplayKey(TimeZone timeZone, boolean daylight, int style,
                           Locale locale) {
			mTimeZone = timeZone;
			if (daylight) {
				style |= 0x80000000;
			}
			mStyle = style;
			mLocale = locale;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int hashCode() {
			return (mStyle * 31 + mLocale.hashCode()) * 31
					+ mTimeZone.hashCode();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public boolean equals(Object obj) {
			if (this == obj) {
				return true;
			}
			if (obj instanceof TimeZoneDisplayKey) {
				TimeZoneDisplayKey other = (TimeZoneDisplayKey) obj;
				return mTimeZone.equals(other.mTimeZone)
						&& mStyle == other.mStyle
						&& mLocale.equals(other.mLocale);
			}
			return false;
		}
	}
}
